Many people wear protective safety helmets while enjoying outdoor riding activities such as snowmobiling, motorcycle riding, and bicycling. While such helmets vary widely in design and features, motorcyclists often choose a helmet design known as a closed face motorcycle helmet. A closed face motorcycle helmet has a hard shell that surrounds and covers a rider's head from the neck up and an eyeport through which the rider can see. A clear shield is hingedly attached to the sides of the helmet and can be flipped down to cover the eyeport for normal use or flipped up out of the way when desired. When the shield is covering the eyeport, a peripheral seal around the eyeport seals against the inside surface of the shield to prevent ingress of air, water, and debris into the interior of the helmet.
Under certain environmental conditions, the inner surface of the shield when closed and sealed is susceptible to condensation formation or “fogging,” which can interfere with a rider's vision and thus must be eliminated. Helmet designers have used several methods to eliminate shield condensation. Such methods include, for example, coating the inside surface of the shield with a hydrophobic coating or designing a helmet vent system that directs outside air into the helmet and across the interior surface of the shield. However, hydrophobic coatings are somewhat but not completely successful and a shield vent system works only when the rider is moving. Another very effective method of clearing a shield fogged with condensation is simply to open the shield to allow outside air into the helmet. However, opening the shield too far while moving can allow high velocity air to hit the riders face and eyes, which is uncomfortable and dangerous. It thus is imperative when employing this method that the shield be opened or cracked by a small amount that is just enough to break contact between the shield and the peripheral seal around the eyeport. Cracking the shield slightly in this way admits a sufficient stream of outside air to clear condensation but does not allow an excessive airflow that might interfere with the rider's comfort or vision.
Most helmets incorporate shield set positions or “detents” through which the shield passes as it is moved from its closed position to its open position. In most cases, however, the first detent or first open position is too large for use in clearing a fogged shield because it allows high velocity air to hit the rider's face and eyes. Some more recent close faced helmets incorporate a mechanism for cracking the shield slightly when desired. The helmet manufacturer Arai, for example, incorporates a small sliding tab on the lower left edge of the helmet shield that, when slid forward, engages a feature on the periphery of the eyeport to cause the shield to rotate slightly upwardly from its closed position. While the Arai and similar systems represent steps in the right direction, they nevertheless tend to have inherent shortcomings. They can, for instance, be difficult to operate, particularly when a rider is wearing gloves.
Another problem encountered by motorcyclists wearing closed face helmets is that the shield of the helmet can accidentally fly open under certain circumstances. For instance, a rider may occasionally rotate his head to view objects outside of his peripheral vision. Similarly, an individual engaging in a high speed race may turn his head to check for other riders to his side or rear. At high speeds, these and similar motions may cause the shield to lift and fly open due to extreme and unbalanced aerodynamic forces.
Thus, there is a need for a closed face helmet with a highly reliable and effective mechanism for cracking the shield of the helmet slightly when desired to remove a condensation fog from the inside surface of the shield. There is a further need for a rider to be able to restrain the shield of the helmet so that it does not accidentally fly open at high speeds when the rider turns or raises his head. These needs should be met without interfering with the normal opening and closing operation of the helmet shield. In addition, the mechanism providing the needed functions should be easily operated even while wearing gloves, should be fail safe to prevent jamming, and should be automatically recoverable in the event of improper or unintended operation by a rider. It is to the provision of a helmet with precision shield control that satisfies all of these needs and more that the present invention is primarily directed.